Heat exchange assembly



Aug? 1959 H. R. OTTO 3,461,956

HEAT EXCHANGE ASSEMBLY Filed Nov. 28. 1967 2 Sheets-$heet 1 FIG- I 5 FIG-2' INVENTOR HOWARD R. OTTO 5 M; ATZRNEY Aug'ts; I969 H. a oT'ro' 3.4.61,956

HEAT EXCHANGE ASSEMBLY Filed Nov. 28. 1967 x 2 Sheets -Sheet 2 FIG-3 l 8 illu LIT INVENTOR HOWARD R. OTTO )fimrrolwvsr United States Patent O HEAT EXCHANGE ASSEMBLY Howard R. Otto, Dayton, Ohio, assignor to United Aircraft Products, Inc., Dayton, Ohio, a corporation of Ohio Filed Nov. 28, 1%7, Ser. No. 686,124

Int. Cl. F28f 3/04; (205:1 23/12 U.S. Cl. 165166 10 Claims ABSTRACT OF THE DISCLOSURE A heat exchanger assembly in which a plate and fin type heat exchanger has uniquely formed plate components for simplified assembly and cooperates with manifolding means mounted to faces of the heat exchanger, the manifolding means including a fluid flow control valve of novel adjustment characteristics.

This invention relates to heat exchange apparatus and has particular, although not limited, reference to plate and fin type heat exchangers and unitarily mounted manifolding and valve means.

An object of the invention is to provide a simplified heat exchanger construction especially characterized by a use of plates which since they are themselves formed with spacer means and with end closures reduce the number of parts required in the assembly and therefore simplify and make less costly the fabrication of the devices.

Another object of the invention is to utilize a structural concept in plate and fin heat exchangers especially suited to constructions in which the parts are joined together by a brazing process, it being proposed to provide built in drain passages in order that the interior of the device may be flushed and drained with facility after brazing, the drain holes being readily closed as a final fabricating step.

A further object of the invention is to provide for a direct mounting of manifolding means to the heat exchanger, a feature of the invention residing in the facility it affords for flowing two confined fluids through the device, both fluids having an inlet and outlet in manifolding means at respective faces of the heat exchanger.

Still another object of the invention is to provide a generally new form of valve control in the manifolding means lending itself to simplified installation and removal and to calibration which does not require repeated assembly and disassembly of the valve.

Other objects and structural details of the invention will appear from the following description, when read in connection with the accompanying drawings, wherein:

FIG. 1 is a view mostly in vertical longitudinal section of a heat exchange device in accordance with the illustrated embodiment of the invention;

FIG. 2 is a view in horizontal longitudinal section through the heat exchange component of the device, showing a fragment of manifolding means at one end thereof;

FIG. 3 is a view in end elevation of the device, showing the closed end of the heat exchange component;

FIG. 4 is a detail view of the open side of the heat exchange component, being taken substantially along the line 4-4 of FIG. 1;

FIG. 5 is a view similar to FIG. 4, showing the open end of the heat exchange component, being taken substantially along the line 5-5 of FIG. 1;

FIG. 6 is a detail view in perspective of one of the plate elements used in the heat exchange component;

FIG. 7 is a detail view in perspective of the other plate element used in the heat exchange component; and

FIG. 8 is a detail fragmentary view of a corner of the heat exchange component showing how a drain opening useful in fabrication of the device is formed.

3,461,955 Patented Aug. 19, 1969 Referring to the drawings, the invention is disclosed as embodied in a device effecting a controlled circulation of two confined fluids in heat transfer relation to one another. Liquid to liquid heat transmission is provided for, the device of the illustrated embodiment of the inven tion being particularly adapted for the cooling of oil in an aircraft or like engine by reference to the relatively cool flowing engine fuel.

The device comprises a heat exchange component 10 and a valve-manifold component 11, mounting brackets 12, 13 and 14 being attached to or forming integral parts of the respective components and serving installation purposes.

The heat exchange component 10 is comprised of stacked plates 15 and 16 (FIGS. 6 and 7), and interposed fin strip material to be subsequently identified, the resulting assembly of. parts forming a plate and fin heat exchanger wherein diiferent fluids flow in adjoining passages for a transfer of heat between separating passage walls. Each plate 15 is rectangular in shape. It is made of a flat, heat conductive, sheet-like material, for example sheet aluminum. Opposite end extremities of each plate are bent upward and then inward. The result is that the ends of the plate are channel shaped and provide seats 17 raised from the flat planar surface of the plate proper. One side margin of each plate 15 is reduced in length to form in effect a projecting tongue which is bent upward and inward to form a seat 18 which extends between and substantially interconnects the seats 17. The length of seat 18 is substantially equal to the distance between the end seats 17. On the other side margin of each plate 15 a smaller length tongue is similarly bent upward and inward to form a seat 19, all of the seats 17, 18 and 19 lie substantially in the same plane. The relatively shorter length of seat 19 defines at opposite ends thereof flow openings 21 and 22.

Each plate 16 is formed similarly to the plate 15 except that in this instance both side margins of the plate are bent upward and inward and define substantially coplanar seats 23 and 24. One end of each plate 16 is bent upward to lie between and interconnect the seats 23 and 24, an end seat 25 being thereby formed. The opposite end extremity of each plate 16 is unformed.

In a stacked relation the plates 15 and 16 have a common orientation. The formed sides thereof, that is, the sides on which the seats 1719 and the seats 23-25 are formed face upwardly. The marginal seats of each underlying plate provide a rest for and support the flat undersurface of a next adjacent overlying plate. Further, all plates 15 face in a common direction and all plates 16 face in a common direction. The plates 15 and 16 are, moreover, stacked in an alternating relation. One side of the resulting assembly since it presents the fluid flow openings 21 and 22 may be considered the open side of the assembly. The opposite side is closed. One end of the assembly, since it is comprised in part of the unformed ends of plates 16 may be considered the open end of the assembly. The opposite end is closed.

The fin strip material which, as described, is interposed between adjacent plates 15 and 16 includes a strip 26 placed on the formed side of each plate 15 in a manner to be confined by the bent over seats 17-19. The strip 26 is formed with corrugations of longitudinal extent and has a height substantially to equal the height of seats 17-19. The strip is positioned so that the corrugations run lengthwise of the plate or in a direction from end to end thereof. At its ends the strip 26 is cut away to define within the confines of end seats 17 generally triangular chambers 27 and 28. Within chamber 27 is a segmental strip 29 of fin strip material constructed like the strip 26 and having the same height but arranged with its corrugations extending lengthwise of the chamber 27 or at 3 right angles to the corrugations of strip 26. In the chamber 28 is a similar strip 31. The chambers 27 and 28 align at their broader ends with the fluid flow openings 21 and 22.

In each plate element 16 is longitudinally disposed a spacer bar 32. The bar 32 is centrally positioned between the side seats 23 and 24. One end thereof coincides with the unformed end of the plate. The bar is shorter than the plate 16 so that the opposite end thereof terminates short of the formed or opposite end of the plate. On each side of the bar 32 are respective strips 33 and 34 of fin material, the fin corrugations extending lengthwise of the plate. One end of each strip 33 and 34 is square to coincide with the corresponding end of bar 32 and with the unformed end of the plate. The opposite ends of the fin strips are cut away along tapered lines to define at what may be considered the closed end of the plate an interior chamber 35.

The fin strip material is installed in the plates and 16 prior to assembly or stacking thereof. The height of the strip material, since it coincides approximately to the height of the marginal seats on the plates provides that it shall be in contact with the flat undersurface of overlying plates. The fin strip material accordingly constitutes extended heat transfer surface, in effect projecting intervening passage walls into the path of flowing fluids. A core assembly includes a plurality of plates 15 and 16 stacked in an alternating relation with strip fin material interposed as described. A flat plate 36 seats on the uppermost plate element, closing the upper end of the core. A stacked core has its component elements joined together in a unitary relation, as by a brazing or like operation. In the brazing process, adjoining plates are secured together along marginal seats and the fin strip material is made to adhere to the sides of confining seats and to overlying and underlying plate surfaces. The structure presents on what has been termed the open side of the device a vertical series of flow openings 21, and, longitudinally spaced therefrom by the turned up seat 19 a vertical set of flow openings 22. The open end of the device is similarly separated by the ends of spacer bars 32 into laterally spaced apart fluid flow openings.

The valve-manifold component 11 includes a valve body 37, a manifold section 38 adapted to make contact with the open side of the heat exchanger component and with another manifold section 39 bent at right angles to the section 38 to contact the open end of the heat exchanger component. A further manifold section 41 also contacts the open end of the heat exchanger component and may be an integral part of the component 11 or, as shown, may be a separate element attached to the section 39.

The manifold section 38 has a flange-like configuration to engage the heat exchanger component along marginal edges thereof. It has, further, interior flanges 42 and 43 engaging the open side of the heat exchanger component intermediate the flow openings 21 and 22. The arrangement accordingly is one to define within manifold section 38 a chamber 44 in common communication with all the inlet openings 21 and a chamber 45 in common communication with all the flow openings 22. Manifold section 39 has a flange marginally contacting one side edge of the heat exchanger component, top and bottom edges thereof and a vertical line of contact defined centrally of the open end of the heat exchanger by the ends of aligned spacer bars 32. A chamber 46 therein communicates with the set of flow openings to one side of spacer bars 32. The manifold section 41 contacts one side edge of the heat exchanger component, top and bottom portions thereof and the exterior of section 39. The arrangement is one to define a chamber 47 in common communication with the lateral set of flow openings to the other side of the spacer bars 32. The valve-manifold component is advantageously welded to the heat exchanger component, welds being formed as indicated along the several lines .4 of contact of the respective described manifold sections with the heat exchanger component.

In the valve body 37 is a chamber 48 communicating through a body port 49 with the chamber 44. Also in the valve body is a chamber 51 in open communication with chamber 45 and communicable through a body port 52 with the chamber 48. Also in the valve body 37 is a chamber 53 communicating through manifold section 39 with chamber 46. Manifold section 41 has an opening 54 therein communicating with chamber 47. Chambers 48, 51 and 53 are connected to the exterior of the valve body by respective openings 55, 56 and 57. All of the openings 54, 55, 56 and 57 are adapted to be connected in lines flowing fluid under pressure, the openings 55 and 56 in a system circulating a first fluid and the openings 54 and 57 in a system circulating a second fluid. In accordance with the illustrated embodiment of the invention openings 55 and 56 are connected in a system circulating oil from and back to a source of heat, opening 55 serving as the oil inlet port through which heated oil from the source of heat is directed to the heat exchanger component while the opening 56 serves as the oil outlet port through which cooled oil is directed from the heat exchanger component back to the source of heat. Openings 54 and 57, in accordance with the invention embodiment, are connected in a system flowing fuel from a source to a place of use. In accordance with such embodiment, opening 54 serves as the fuel inlet port, fuel flowing from the source through such opening being directed to the heat exchanger component. Opening 57 serves as the fuel outlet port, fuel being directed therethrough from the heat exchanger component to the place of use.

In accordance with the mode of operation of the heat exchange device, oil enters the device by way of oil inlet port 55, flows through chamber 48 and opening 49 to chamber 44. There it has simultaneous access to all of the flow openings 21 and so enters the several flow passages defined by plates 15. The oil initially encounters strip fin material 29, is guided thereby interiorly of the heat exchanger within chamber 27. From there it flows lengthwise of the heat exchanger along a path as defined by strip material 26 to chamber 28 whereupon it turns and is redirected by strip fin material 31 to and through the flow openings 22. Emptying into chamber 45, the oil flows to chamber 51 and leaves the device by way of oil outlet port 56. Fuel entering fuel inlet port 54 is distributed in chamber 47 to flow simultaneously through the several plates 16 along paths as defined by the strip fins 33 along one side of the spacer bars 32. Entering chamber 35 at the far end of each plate 16, the fuel turns and flows in a reverse direction along the opposite side of bars 32 along fin strips 34, emptying into chamber 46. There the fuel is conducted by manifold section 39 to valve body chamber 53 and leaves the device by way of fuel outlet port 57. In the presence of oil and fuel flows as described, it will be understood that some of the heat of the relatively higher temperature oil is transmitted through encountered fin strip material and through the separating passage walls to the lower temperature fuel. Oil leaving the device by way of oil outlet port 56 is conditioned to a lower temperature value suitably to its return to the heat source.

The body opening 52 provides for direct flow of greater or lesser portions of the oil admitted by way of inlet port 55 to outlet port 56 in by-passing relation to the heat exchange component. By-passing flow occurs, under control of a valve 57, under conditions indicating excessive oil cooling or in the event that the difference in pressure value between inlet port 55 and outlet port 56 is such that heat exchange component 10 may be damaged thereby. The valve 57 is a disc-shaped member having a flanged periphery adapted to seat on a vertical partition 58 in which opening 52 is formed. The valve is in chamber 51 and seats to the partition 58 in a surrounding relation to opening 52 but in a manner to yield to relatively higher pressures in chamber 48 to move to an unseated, open position. Ex-

tending in one direction from the valve 57 is an integrally formed stem 59 received for relative longitudinal sliding motion in a bushing 61. The latter is formed integrally with a large diameter nut 62 having a screw threaded mounting in an end opening 63 in the body 37. End opening 63 and by-pass opening 52 are aligned. Nut 62 and bushing 61 are in concentric relation to opening 63 and so guide the valve 57 concentrically of by-pass opening 52. A compression spring 64 is interposed between the back of valve 57 and an integral flange on bushing 61 in a manner to urge the valve yieldingly to a seated position on partition 58. The nut 62 acts as a closure cap for one end of the body 37 but is adjustable in a rotary sense from outside the body, the screw threaded mounting of the nut being such that rotary turning movement of the nut effects axial longitudinal adjustments thereof in a manner to vary the compression of spring 64. A cylindrical portion of nut 62 has a bearing in an inwardly projecting boss 65 of the body 37. A sealing member 66 is peripherally installed in such cylindrical portion to inhibit the escape of oil from chambers 45 and 51. The valve- 57 is further formed with an oppositely projecting stem 67, extending to and through the by-pass opening 52 into chamber 48.

The end of body 37 opposite opening 63 is formed with another like opening 68, the openings 63 and 68 being aligned. An externally threaded nut 69 is rotatable in the opening 68 and has a projecting sleeve portion 71 guided by a bearing surface 72. A peripheral seal 73 in sleeve 71 engages surface 72 and inhibits escapeof fuel from chamber 53. Centrally of the sleeve 71, the nut 69 is formed with a relatively shorter projection 74. Seated on the projection 74 is one end of a thermostat 75 the other end of which is slidingly mounted in a counterbore 76 of a bore 77 opening into chamber 48. The thermostat 75 is of a known construction wherein a case 78 thereof contains a temperature sensitive material which when heated expands with a substantial working ability. Since the case 78 reacts on projection 74 and since it otherwise confines the expansible material, the expansive force is resolved into an outward thrust of a plunger 79 in an axial sense. The said other end of the thermostat, through which plunger 79 projects, is surrounded by a seal 80 inhibiting leakage between the oil and fuel circuits. An interponent rod 81 engages at its one end the plunger 79, extends axially through counterbore 76 and bore 77 into chamber 48 where it abuts stem 67 of valve 57, the stem 67 and rod 81 being axially aligned. A compression spring 82 is confined in counterbore 76 and urges the rod 81 into continuous contact with the plunger 79, this spring serving a further function in returning plunger 79 inward and re-compressing the temperature sensitive material in case 78 under lowering temperature conditions.

The thermostat 75 is disposed in chamber 53 in the path of fuel flowing to the fuel outport 57. It accordingly senses the temperature of the fuel after leaving the heat exchange component and after absorbing heat from the oil with which it has been in heat transfer relation in the heat exchange component. Rising and lowering fuel temperatures bring about extension and retraction of the plunger 79. An increase in what may be termed fuel out temperature above a selected value, indicating excessive oil cooling, results in the rod 81 being projected sufficiently to unseat valve 57. A greater or lesser amount of oil is permitted under this condition to flow directly through opening 52 to the oil outlet port 56, by-passing the heat exchange component. A mixture of cooled and uncooled oil will leave the device by way of outlet port 56, it being understood that the construction and arrangement of parts is such as to return conditioned oil from the heat exchange device at a substantially constant temperature.

The valve construction lends itself to simplified assembly and disassembly, as well as simplified form of calibration. Removal of the end closures 62 and 69 provides wide openings at opposite ends of the valve body through which the thermostat and valve components may be readily installed and removed. All elements of the valve are in line with one another and readily accessible. Calibration of the valve is possible after assembly and does not require that parts he removed for machining or adjustment or in order that shims may be inserted or removed. Thus, after assembly, in a test stand installation oil is circulated through the oil side circuit, that is, into the device by way of inlet port 55, through passage 48 and back to the oil outlet port by way of chamber 51. The valve body 37 may or may not be welded to the heat exchange component at this time. The pressure of the incoming oil is raised until a pressure differential between the oil inlet port 55 and the oil outlet port 56 reaches a value which has been predetermined to be the value at which it is desired that valve 57 should open. Should valve 57 open prior to the reaching of this pressure difference, end closure nut 62 is rotated to compress spring 64 and apply a greater thrust to valve 57 in a closing direction. Should the valve 57 remain closed after the predetermined pressure difference has been reached, the end closure 62 is rotated in an opposite sense to relive the compression of spring 64. Incremental adjustments of the nut 62 are made in this manner as required to arrive at a proper, selected opening pressure for valve 57.

In calibrating thermostat 75, fuel is put through the fuel side circuit with the temperature being raised to a selected value, beyond which higher temperatures indicate excessive cooling. It is desired that at or about the selected high temperature value rod 81 should engage stem 67 and unseat valve 57. Accordingly, with the fuel out temperature stabilized at the high selected value, the peripherally threaded end closure 69 is adjusted as required to effect corresponding longitudinal adjustments of the thermostat 75. At the selected temperature value plunger 79 is extended a predetermined distance. This distance should be enough so that the extremity of rod 81 contacts the extremityof stem 67 without, however, unseating valve 57. 'If the parts are not so positioned end closure 69 is adjusted for axial re-positioning of thermostat 75 to bring about the desired relationship of the parts. The relative position of the stem 67 and rod 81 may be visually and hand checked through the oil inlet port 55.

Referring to the heat exchanger component, the bending upward and inward of marginal edges of the plates 15 and 16 create channels which are open where not closed by the manifold sections 38, '39 or 41. Thus, and referring to FIG. 8 for example, the plate 16 has at What may be considered its closed end small laterally spaced openings 83. Similar openings are formed at opposite ends of the assembly in plates 15, at What may be considered the closed side thereof. In final assembly sets these openings serve a useful purpose since they allow flushing and draining of the heat exchanger interior. The salts used in the brazing process have a corrosive effect if allowed to remain after brazing. The holes 83 provide convenient and effective drains assuring a clean, corrosion resistant interior for the heat exchanger component. After flushing and draining the openings '83 may be closed by the deposit of weld metal.

The invention, as noted, has particular reference to oil cooling and like devices, particularly devices of this nature made small, compact and light weight for aircraft and similar use. The invention has, however, general application to heat exchangers and heat exchanger-valve combinations. Further, it is apparent that the apparatus lends itself to extensive structural modification without deparing from the spirit of the invention as disclosed.

The plates 15 and 16 have been described as being in an alternating arrangement, this being optional for most efficient heat transfer. Like plates may be adjacent to one another, however, where dimensional or other circumstances may require. In the illustrated instance a pair of '7 plates are superposed in the mid section of the heat exchanger.

While chambers 27 and 28, and segmental fins 29 and 31 therein have been described as generally triangular, base portions thereof have parallel sides. The result is to achieve a guided flow of the oil in a manner to inhibit short circuiting between openings 21 and 22. Oil entering opening 21 is restrained from turning and moving immediately to opening 22. Instead it is guided to interior portions of fin strip 26, making maximum use of provided heat transfer surface.

What is claimed is:

1. A heat exchanger assembly, comprising:

(1) A heat exchanger made up of:

(a) A first plate rectangular in configuration and made of a flat heat conductive sheet metal or like material, marginal side edges of said plate being bent upward and then reversely inward to define closed side channels and marginal seats spaced from the body of the plate, the portion of one end of the plate between said side channels being similarly formed, the opposite end of the plate being open;

(b) A second plate constructed like the first plate but having both ends and both side margins bent upward and inward, an intermediate portion only of one side margin being bent to define longitudinally spaced openings along one side margin; said first and second plates being stacked one upon another in positions of common orientation with the underside of the upper plate seating on the upturned edges of the lower plate and being spaced thereby from the flat body of the lower plate, a chamber being formed between said plates which opens either through one end of the stacked assembly or through said longitudinally spaced side openings depending on which of said first and second plates is the upper plate; a plurality of said first and second plates being stacked in an alternating relation to define multiple chambers alternating ones of which open respectively through said one end of the assembly and through said side openings, the configurations of said plates giving said assembly an open end and a closed end and an open side and a closed side;

(c) A division member longitudinally disposed in each end opening chamber to extend centrally thereof from the open end of the assembly toward but short of the closed end, said member making common contact with overlying and underlying plate bodies to define laterally spaced apart end opening at each of the end opening chambers;

(d) Extended surface strip fin material disposed in said chambers;

(e) Means securing the elements of the heat exchanger into a unitary structure;

(2) Manifolding means mounted to the open end of the heat exchanger assembly having separated chambers in respective communication with separate sets of laterally spaced apart openings therein, and other manifolding means mounted to the open side of said heat exchanger assembly and having separated cham Ibers in respective communication with separated sets of longitudinally spaced side openings; and

(3) Means for flowing first and second fluids through said heat exchanger assembly by way of said manifolding means, a first fluid entering a chamber in the first said manifolding means simultaneously entering a communicating set of laterally spaced openings to flow longitudinally within the assembly along one side of said division members then turn and come back along the other side of the division members to exit through the other set of laterally spaced openings into the other chamber in said first manifolding means, a second fluid entering a chamber in said other manifolding means simultaneously entering a communicating set of longitudinally spaced openings to flow laterally into the assembly then turn and flow longitudinally thereof and turn again to flow laterally out of the assembly by way of the other set of longitudinally spaced openings into the other chamber in said other manifolding means.

2. A heat exchanger assembly according to claim 1, characterized by means applied to close corner openings formed in said stacked assembly at the closed end thereof and at the closed side thereof by the bending of said marginal edges, said corner openings serving a useful purpose in allowing flushing and draining of the heat exchanger interior during fabrication and being thereafter closed.

3. A heat exchanger assembly according to claim 1, characterized in that said division members are solid metallic bars having their outer ends terminating in the plane of the open end of the heat exchanger assembly, the several superposed bars forming in conjunction with intervening closed ends of said second plates a line of contact for a portion of the first said manifolding means whereby sets of laterally spaced apart openings are separated from one another.

4. A heat exchanger assembly according to claim 1, characterized in that said manifolding means is comprised at least in part of a unitary valve body having flow passages for said first and second fluids and having further valve means therein responding to a changing condition of one fluid to control flow of the other.

5. A heat exchanger assembly according to claim 1, characterized in that the strip fin material in the heat exchanger chambers opening through said open side of the assembly comprises in each instance a first member disposed with its fins extending longitudinally of the assembly and terminating short of the ends thereof and second and third members disposed in the ends of the chamber opposite respective longitudinally spaced openings, said second and third members having their fins extending at right angles to those of said first member, the arrangement being one in which fluid entering the chamber is guided by a said second fin member into the chamber, is guided by said first fin member longitudinally of the chamber and is guided by said third fin member out of the chamber, the adjacent edges of aid first and second fins and of said first and third fins being tapered for a more facile interchange of fluid therebetween.

6. A heat exchanger assembly according to claim 1, characterized in the said manifolding means is comprised of a body having integral portions mounting to the open side and open end of said assembly, a first portion of said body achieving a line of contact with said Open side at end extremities thereof in a manner to close the channels defined by the turned over ends of said second plates and said second body achieving further a contact of said open side at the location of said intermediate bent edges of said second plates whereby to separate said longitudinally spaced side openings, and a second portion of said body achieving lines of contact with the open end of said assembly at side extremities thereof closing channels in said first plates and along a central dividing line represented by the superposed series of division member, said manifolding means being unitarily joined to said heat exchanger assembly along said lines of contact.

7. A heat exchanger assembly according to claim 6, wherein said manifolding means is unitarily joined to said heat exchanger assembly by welding, channels opening through the closed end and the closed side of said heat exchanger assembly being closed by deposit of weld metal.

8. A heat exchanger core constructed by stacking in a superposed aligned relation alternating first and second plates with extended surface fin material therebetween, each first plate being comprised of a rectangular planar member made of heat conductive material, side margins being bent upward to define raised edges and bent over toward one another to define marginal seats elevated relatively to the planar body of the plate, one end of the plate being made of reduced width to correspond approximately to the distance between said marginal seats and being bent upward and inward to form a similar raised marginal seat at said one end embraced between and interconnecting said side seats, each second plate being constructed like each first plate except that ends thereof are formed with raised marginal seats and one side margin thereof is reduced and formed with a side raised marginal seat embraced by and interconnecting said end marginal seats, extended surface fin material resting on each plate confined by said marginal seats and having a height corresponding approximately to the height of said seats, an overlying plate resting on the marginal seat of an underlying plate with intermediate fin material substantially compresed between the plates, said plates being oriented to define an assembly having a closed end and an open end and a closed side and an open side, means providing for flow of a first fluid into and out of the heat exchanger assembly by way of said open end and for flow of a second fluid into and out of the heat exchanger assembly by way of said open side, and means for joining said plates in a unitary relation.

9. A heat exchanger core according to claim 8, characterized by means for closing the corner openings occurring at the closed end and at the closed side of the heat exchanger core at the extremities of the interconnecting marginal seats.

10. A plate and fin assembly in a plate and fin heat exchanger, including a heat conductive plate having opposing sides and ends, means defining raised margins on said plate, said means providing along one side of the plate spaced apertures for inflow and outflow of a fluid, and strip fin material disposed to lie flat on said plate confined by said margins, said material including a first strip intermediate the ends of the plate having its fins extending approximately parallel to the plate sides, said material further including second and third strips disposed like said first strip but at opposite ends thereof and with their fins at right angles thereto, base portions of said second and third strips extending to one substantially within respective apertures and having parallel sides, a side of each of said second and third strip above said base portion being tapered and the adjacent end of said first strip being tapered in complementary fashion for a guided distributed flow over said plate and intermediate strip fin in which short circuiting flow between apertures is inhibited.

References Cited UNITED STATES PATENTS 2,778,606 1/1957 Lloyd et al --37 2,809,810 10/1957 Carroll et al. 165-37 3,282,334 11/1966 Stahlheber 165-166 3,380,517 4/1968 Butt 165-166 ROBERT A. OLEARY, Primary Examiner C. SUKALO, Assistant Examiner US. Cl. X.R. 

